The agriculture industry encounters regular challenges related to preserving and shipping produce prone to spoilage. Typically, produce is shipped in thin film vented PE plastic bags, corrugated containers or trays, mesh bags or vented clamshells. When most produce, such as fruit, is shipped it can be abused in transit. This transportation abuse can accelerate the ripening of fruit or damage the fruit, which also leads to accelerated ripening, browning and/or bruising of the surrounding fruit. This bruising is a result of oxidation of compounds within the fruit. To limit this damage, chemical barriers are sometimes employed. One example of a chemical barrier is citric acid, which is highly reactive to oxygen and thus reduces the oxidation of the produce itself. In addition to oxidation, damage to produce exposes the nutrients within the produce cells. This exposure leads to the colonization of microbes such as E. coli and Salmonella, as well as molds, fungi, and yeasts. To reduce this colonization, produce is sometimes dehydrated slightly. It is believed that the dehydration improves the threshold at which the product bruises. In some cases, produce is refrigerated to a temperature of 32 degrees Fahrenheit to slow the ripening process or extend the shelf life during storage or transportation.
Frequent causes of produce bruising include impact between closely packed pieces of produce and between produce and shipping containers. Larger and more massive produce can also be damaged due to the weight of one piece of produce on another. Visco-elastic properties of some produce can worsen the damage. Damage also has a tendency to release certain gases, such as ethylene, which causes some produce to increase the rate or ripening. For example, climacteric fruits continue ripening after picking and thus are susceptible to accelerated ripening by ethylene. Leaves, such as lettuce, are also susceptible to this ripening process. It is believed that ethylene affects the genes that make enzymes. The enzymes then catalyze reactions to alter the characteristics of the produce. The action of the enzymes causes the ripening responses. Chlorophyll is broken down and sometimes new pigments are made so that the fruit skin changes color from green to red, yellow, or blue. Acids are broken down so that the fruit changes from sour to neutral. The degradation of starch by amylase produces sugar. This reduces the mealy (floury) quality and increases juiciness. The breakdown of pectin, thanks to pectinase between the fruit cells, unglues them so they can slip past each other. That results in a softer fruit. Enzymes also break down large organic molecules into smaller ones that can be volatile (evaporate into the air) and that we can detect as an aroma. Producing the ethylene also causes more ethylene to be produced. During the shipping process the ripening and spoiling of fruit is generally considered to be negative. For example in grapes there is not only the bruising but once the grape breaks from the stem or twists on the stem the open wound begins to oxidize and start to decay because the flesh is exposed to mold spores that are in the atmosphere. By added protection during shipping produce shelf life can be extended up to 60 days. It's not necessarily how fast it will accelerate but the fact that there are berries that are breaking down the buyer won't be interested in buying the product making it worthless.
In order to reduce ripening and spoiling, numerous solutions have been offered. Some of these solutions include partial dehydration, air circulation around the fruit, open storage systems (e.g. open box), chemical prevention (e.g. citric acid), modifying equipment and handling procedure, or pre-conditioning fruit (hydration/temp); cold temperature storage; charcoal scrubbing of the produce atmosphere to absorb ethylene use of carbon dioxide and nitrogen as ripening inhibitors; physical separation with cardboard (or similar) dividers; and other process. These processes tend to be costly, cumbersome, or undesirable to the quality of the produce. As such, improved systems and methods may be desirable in the industry.